Telescopic crane boom

ABSTRACT

OUTER TUBE HAVING A CYLINDER THEREON MOVING A CARRIAGE THEREALONG, A MULTIPLE PULLEY SYSTEM ACTUATED BY THE CARRIAGE FOR PROPELLING A MIDDLE TUBE OUT OF THE OUTER TUBE, AND A PULLEY SYSTEM ON THE MIDDLE TUBE ACTUATED BY PROPULSION THEREOF FOR PROPELLING AN INNER TUBE OUT OF THE MIDDLE TUBE.

Sept. 20, 1971 EY 3,605,358

TELESCOPIC CRANE BOOM Filed March 28, 1969 2 Sheets-Sheet 1 INVENTOR. JOSEPH 7.' BENTEY Attorney Sept. 20, 1971 Filed March 28, 1969 J. T. BENTEY TELESCOPIC CRANE BOOM 2 Sheets-Sheet 2 INVENTOK JOSEPH I BENTEY Attorney WA/M United States Patent 3,605,358 TELESCOPIC CRANE BOOM Joseph T. Bentey, Cliff St., West Orange, NJ.

Filed Mar. 28, 1969, Ser. No. 811,564 Int. Cl. E04h 12/34 US. Cl. 52-121 3 Claims ABSTRACT OF THE DISCLOSURE Outer tube having a cylinder thereon moving a carriage therealong, a multiple pulley system actuated by the carriage for propelling a middle tube out of the outer tube, and a pulley system on the middle tube actuated by propulsion thereof for propelling an inner tube out of the middle tube.

BACKGROUND According to the present invention, the telescopic crane boom comprises outer, middle, and inner tubes, a carriage movable along the outer tube, a pulley system actuated by the carriage, a cable passing over said pulley system from said outer tube to said middle tube, and means for' moving the carriage down the outer tube to raise the middle tube. A second cable passing over a pulley on the inside of the outer end of the middle tube pulls an inner tube forward. The first pulley system comprises a first group of pulleys on the carriage and a second group on fixed axes at the bottom of the outer tube, over which groups the first cable passes alternately and in succession.

DRAWINGS FIG. 1 is a side elevation of a motor truck for carrying a telescopic crane boom;

FIG. 2 is a plan of the boom shown in FIG. 1, showing the structure according to the present invention; and

FIG. 3 is a vertical longitudinal section taken along the line 33 of FIG. 2.

DESCRIPTION As shown in FIG. 1, a motor truck is provided with a pedestal 12 on which is mounted an outer telescopic boom tube 20 pivoted at 14 and'swung up thereabout by a cylinder 16 to lift a receptacle such as a basket 18.

As better shown in FIGS. 2 and 3, the outer tube 20 has slidable therein a middle tube 22 which in turn has slidable therein an inner tube 24. A' carriage 26 is slidably mounted on the outer tube 20 intermediate the ends thereof, and has journaled thereon a group of pulleys 28. The carriage 26 is selectively moveaible back and forth by the piston of a cylinder 30 mounted on the outer tube 20. K

A cable 32 has one end fixed as at 33 to the top end portion of the outer tube 20, and passes under the outer pulley 34 of group 28 and up thereover on down over a fixed axis pulley 36, then under a second pulley 38 of group 28 over a second fixed axis pulley 40. From this pulley the cable 32 passes down through a suitable aperture and on back to loop around a bitt 42 secured on the bottom end portion of the middle tube 22.

3,605,358 Patented Sept. 20, 1971 From the bitt 42 the cable 32 follows a symmetrical path for the other side of the outer tube 20', and the other end is similarly fixed to the top end portion of the outer tube.

With this pulley system, when the piston of the cylinder 30 pushes the carriage 26 toward the bottom, the cable 32 looped over the bit 42 pulls the middle tube 22 outward and upward with a multiple factor of four.

As shown in FIG. 3, a second cable 44 is attached at 46 inside the bottom of the outer tube 20*, and extends upward inside the middle tube 22, on around pulley 48 inside the top thereof, from which it returns inside the middle tube 22 and is attached at 49 to the bottom of the inner tube 24.

As the middle tube moves upward as already described, it carries the pulley 48 therewith. The cable 44 passing thereover is pulled therealong, and propels inner tube 24 upward, twice as far as tube 22, with a factor of eight relative to the movement of the piston of cylinder 30'.

As shown in FIG. 2, a third cable '50 is fixed at 52 to the bottom end of the outer tube 20', and passes under the first of the middle pulleys 54 of the group 28 on the carriage. A rear set of fixed axis pulleys 56 are mounted on the bottom end portion of the outer tube 20. The cable 50 passes over the pulleys 54 and 56 alternately and in succession, then on down over the pulley 58. From this pulley the cable 50 passes under the pulley 60 below the bottom of the middle tube 22, where it is attached at 62 to the bottom end of the inner tube 24.

To collapse the extended boom, the piston of cylinder 30 is energized to move the carriage 26 upward toward the outer end of the boom. The middle pulleys 54 pull the third cable 50 about the pulleys 56 and 58 to pull down the inner tube 24 to which it is attached at 62. The second cable 44 being attached at 49 to this inner tube 24, pulls on the pulley 48 inside the top of middle tube 22, to pull it back inside the outer tube 20.

During this collapsing movement of the piston of cylinder 30, the first cable 32 is slackened, which permits the bitt 42 to pull the slackened cable with it for the return of the middle tube 22.

What is claimed is:

1. Telescopic crane boom comprising outer, middle and inner tubes;

a carriage movable along said outer tube intermediate the ends thereof;

power cylinder means connected between said carriage and outer tube for moving said carriage;

a pulley system carried by said carriage;

a cable having one end anchored to said outer tube and passing over one part of said pulley system and around a bitt on said middle tube and on over a symmetrical path of said pulley system with the other end also anchored to said middle outer tube;

means for moving said carriage toward the bottom of said outer tube to propel said middle tube outward from inside of said outer tube;

a pulley secured to the upper end of said middle tube;

a second cable having one end secured to the bottom of said outer tube and passing over said pulley on said middle tube and back and secured to the bottom of said inner tube;

said second cable being actuated by said movement of said middle tube for pulling said second cable over said middle tube pulley to move said inner tube out of said middle tube;

a fourth group of pulleys journaled on fixed axes near the bottom end of said outer tube; and

a third cable having one end anchored to the bottom end portion of said outer tube, and passing over said third and fourth group pulleys alternately and in succession, and having the other end anchored to the bottom end portion of said inner tube.

2. Telescopic crane boom as claimed in claim 1, in which said means for propelling said middle tube outward from the inside of said outer tube and said means for propelling said inner tube outward from inside of said middle tube are operated by the same single prime mover.

3. Telescopic crane boom as claimed in claim 1, in which said pulley is secured to the upper end of said middle tube is mounted inside thereof.

References Cited UNITED STATES PATENTS 2,885,799 5/1959 LeTourneau 254l43 10/1964. Worthington- 212-55 3/1967 Bopp 212'55- 9/1969 Reuter 212-55 2/1956 Chesher 187---10 8/1966 Stefanutti 212 FOREIGN PATENTS: q 5/1958 Germany 212- 10 HARVEY C. HORNSBY, Primary Examiner US. 01. X.R.

6/1963 Winter 212-55 15 

